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Dr. Hsiehis a senior resident in the UCLA/Olive View emergency medicine residency program.Dr. Lovatois an associate professor at the David Geffen School of Medicine at UCLA, the ED director of clinical practice at Olive View-UCLA Medical Center, and the co-chair for the Emergency Medicine Best Practices Committee for the Los Angeles County Department of Health Services.

Experienced emergency physicians tend to focus on questions (and answers) that have the greatest impact on management when they interview patients. Assessing for medications that predispose to bleeding, for instance, ranks high on the list of priorities for blunt head trauma patients. No matter how good a patient looks or how normal his neurological exam, certain agents persuasively sway the risk-benefit balance toward imaging.

Patients taking warfarin or clopidogrel are at increased risk for traumatic intracranial hemorrhage, including parenchymal, subarachnoid, subdural, and epidural bleeds, even after mild head trauma. (J Trauma 2002;53[4]:668, Am J Surg 2006;192[6]:743.) Established guidelines clearly recommend head CT for patients taking warfarin (Eur J Neurol 2002;9[3]:207), but it is less clear what to do with minor head trauma patients taking clopidogrel. Questions remain about the need for extended observation and serial imaging and the safety of discharging patients at risk for delayed bleeding, even after a negative head CT. One recent retrospective review found a one percent incidence of delayed intracranial hemorrhage in patients on anticoagulant or antiplatelet therapy, although none was clinically significant. (J Trauma 2011;71[6]:1600.) Now, two studies published in June serve to clarify management of these patients in the ED.

Immediate and Delayed Traumatic Intracranial Hemorrhage in Patients with Head Trauma and Preinjury Warfarin or Clopidogrel Use

Management of Minor Head Injury in Patients Receiving Oral Anticoagulant Therapy: A Prospective Study of a 24-hour Observation Protocol

Menditto VG, et alAnn Emerg Med2012;59(6):451

The study by Nishijima et al was a large prospective, observational study at two trauma centers and four community hospitals of 1,064 adults with preinjury (less than seven days), warfarin or clopidogrel use, and blunt head trauma. Exclusion criteria included transfer from outside hospitals or the use of warfarin and clopidogrel concomitantly. One thousand patients received a head CT in the ED; patients did not receive serial imaging per study protocol, but were followed by telephone or electronic health record review to assess for delayed hemorrhage.

Delayed hemorrhage was defined as traumatic intracranial hemorrhage within two weeks after an initial negative CT scan, barring repeated head injury. The majority of patients (72.2%) were on warfarin, with similar demographic characteristics to those on clopidogrel.

More patients on clopidogrel had immediate traumatic intracranial hemorrhage (12%; 95% CI 8.4% to 16.4%) than patients on warfarin (5.1%; 95% CI 3.6% to 7.0%), relative risk (2.31; 95% CI 1.48 to 3.63). Patients on warfarin were more likely to have delayed traumatic intracranial hemorrhage (0.6%; 95% CI 0.2% to 1.5%), however, with no cases identified in the clopidogrel patients.

The authors concluded that delayed traumatic intracranial hemorrhage is a rare entity with an incidence of less than one percent in both populations. Serial CTs were not obtained, however, so the incidence of delayed hemorrhage may have been underestimated.

Menditto et al conducted another prospective observational study at a Level II trauma center in Italy that evaluated 97 consecutive patients on warfarin who had no acute findings on initial head CT after minor head trauma. The study implemented a protocol for these patients based on the 2002 recommendations from the European Federation of Neurological Societies, which included 24 hours of observation with neurologic checks every four to six hours and a second head CT prior to discharge. (Eur J Neurol 2002;9[3]:207.) Outcomes included presence of an intracranial bleed or other traumatic process on the second CT scan, death, admission for CT abnormality, neurosurgery, or readmission within 30 days for symptoms related to head injury.

The second head CT demonstrated a bleed in five patients (6%), three of whom were admitted and one who underwent craniotomy. Two other patients discharged after serial negative CT scans became symptomatic and were readmitted two and eight days later with subdural hematomas; neither required surgery. Both patients had INRs greater than 3.0, but the study was not powered to determine predictors of intracranial bleeding. This study was limited by its small size and single location. Ten patients refused the second CT scan required by the protocol, but were clinically well at 30-day follow-up.

It should be a no-brainer to obtain a head CT on any patient with mild head trauma who is taking clopidogrel or warfarin. Incidence of intracranial hemorrhage is relatively high, especially in the clopidogrel group (12%), regardless of clinical status. The patients on clopidogrel described in these studies who did not have an acute intracranial hemorrhage on CT may be safely discharged with traditional head injury return precautions and follow-up. Sending these patients home is reasonable because the prevalence of a clinically significant delayed bleed is extremely low.

Unfortunately, managing patients on warfarin with mild head trauma and a negative head CT remains a little less certain. No EP would not be faulted for admitting these patients for 24 hours of observation, serial neurological checks, and serial CT given the findings of the Menditto study and a six percent incidence of delayed bleeding. This is especially true if the INR at presentation is higher than 3.0 because this subgroup appears to be at highest risk. The larger Nishijima study suggests, however, that the risk of clinically significant delayed intracranial hemorrhage in these patients is really much lower (0.6%). Discharge home with close follow-up and appropriate understanding of return precautions is also reasonable, reserving observation or admission for cases when these cannot be guaranteed.

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